Solar cell including conductive amorphous semiconductor layer and method of manufacturing solar cell

Abstract

An i-type layer is formed on a side of one surface of a crystalline semiconductor substrate. An n-type layer or a p-type layer is formed on the i-type layer and includes a conductive impurity. A TCO is formed on the n-type layer or the p-type layer. A density in a proximate portion of the n-type layer or the p-type layer closer to the TCO than a remote portion of the n-type layer or the p-type layer is smaller than a density in the remote portion.

What is claimed is: 
     
         1 . A solar cell comprising:
 a crystalline semiconductor substrate;   an intrinsic amorphous semiconductor layer formed on a side of one surface of the crystalline semiconductor substrate;   a conductive amorphous semiconductor layer formed on the intrinsic amorphous semiconductor layer and including a conductive impurity; and   a transparent conductive film layer formed on the conductive amorphous semiconductor layer, wherein   a density in a second portion of the conductive amorphous semiconductor layer closer to the transparent conductive film layer than a first portion of the conductive amorphous semiconductor layer is smaller than a density in the first portion.   
     
     
         2 . The solar cell according to  claim 1 , wherein
 a dopant concentration in the second portion of the conductive amorphous semiconductor layer is smaller than a dopant concentration in the first portion.   
     
     
         3 . The solar cell according to  claim 1 , further comprising:
 a further intrinsic amorphous semiconductor layer;   a further conductive amorphous semiconductor layer including a conductive impurity; and   a further transparent conductive film layer, wherein   the further intrinsic amorphous semiconductor layer, the further conductive amorphous semiconductor layer, and the further transparent conductive film layer are formed on a side of the crystalline semiconductor substrate opposite to the intrinsic amorphous semiconductor layer, the conductive amorphous semiconductor layer, and the transparent conductive film layer,   a conductivity type of the impurity included in the further conductive amorphous semiconductor layer is different from a conductivity type of the impurity included in the conductive amorphous semiconductor layer, and   a density in a fourth portion of the further conductive amorphous semiconductor layer closer to the further transparent conductive film layer than a third portion of the further conductive amorphous semiconductor layer is smaller than a density in the third portion.   
     
     
         4 . The solar cell according to  claim 2 , further comprising:
 a further intrinsic amorphous semiconductor layer;   a further conductive amorphous semiconductor layer including a conductive impurity; and   a further transparent conductive film layer, wherein   the further intrinsic amorphous semiconductor layer, the further conductive amorphous semiconductor layer, and the further transparent conductive film layer are formed on a side of the crystalline semiconductor substrate opposite to the intrinsic amorphous semiconductor layer, the conductive amorphous semiconductor layer, and the transparent conductive film layer,   a conductivity type of the impurity included in the further conductive amorphous semiconductor layer is different from a conductivity type of the impurity included in the conductive amorphous semiconductor layer, and   a density in a fourth portion of the further conductive amorphous semiconductor layer closer to the further transparent conductive film layer than a third portion of the further conductive amorphous semiconductor layer is smaller than a density in the third portion.   
     
     
         5 . A method of manufacturing a solar cell comprising:
 forming an intrinsic amorphous semiconductor layer on a side of one surface of a crystalline semiconductor substrate masked at least in part;   forming a conductive amorphous semiconductor layer including a conductive impurity on the intrinsic amorphous semiconductor layer; and   forming a transparent conductive film layer on the conductive amorphous semiconductor layer, wherein   a deposition speed for forming a second portion of the conductive amorphous semiconductor layer closer to the transparent conductive film layer than a first portion of the conductive amorphous semiconductor layer is higher than a deposition speed for forming the first portion.   
     
     
         6 . The method of manufacturing a solar cell according to  claim 5 , wherein
 the deposition speed for forming the second portion of the conductive amorphous semiconductor layer is 1.01 times-5.00 times the deposition speed for forming the first portion.